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Date:   Fri, 15 Apr 2022 12:57:56 +0200
From:   Oleg Nesterov <oleg@redhat.com>
To:     Peter Zijlstra <peterz@infradead.org>
Cc:     rjw@rjwysocki.net, mingo@kernel.org, vincent.guittot@linaro.org,
        dietmar.eggemann@arm.com, rostedt@goodmis.org, mgorman@suse.de,
        ebiederm@xmission.com, bigeasy@linutronix.de,
        Will Deacon <will@kernel.org>, linux-kernel@vger.kernel.org,
        tj@kernel.org, linux-pm@vger.kernel.org
Subject: Re: [PATCH 2/5] sched,ptrace: Fix ptrace_check_attach() vs PREEMPT_RT
Message-ID: <20220415105755.GA15217@redhat.com>
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On 04/15, Oleg Nesterov wrote:
>
> OK, so far it seems that this patch needs a couple of simple fixes you
> pointed out, but before I send V2:
>
> 	- do you agree we can avoid JOBCTL_TRACED_FROZEN in 1-2 ?
>
> 	- will you agree if I change ptrace_freeze_traced() to rely
> 	  on __state == TASK_TRACED rather than task_is_traced() ?
>

Forgot to say, I think 1/5 needs some changes in any case...

ptrace_resume() does  wake_up_state(child, __TASK_TRACED) but doesn't
clear JOBCTL_TRACED. The "else" branch in ptrace_stop() leaks this flag
too. Perhaps I missed something, I'll reread 1/5 again, but the main
question to me is whether 1-2 actually need the JOBCTL_TRACED_FROZEN flag.

Oleg.